This invention relates to a poly(arylene sulfide) composition, to a molding method and to an electronic component. In one embodiment, the invention relates to a composition and method for improving the hydrolytic stability of a poly(arylene sulfide) molded article. In another aspect, the invention relates to an electronic component in which a poly(arylene sulfide) molded part is in contact with a liquid electrolyte.
Poly(arylene sulfide) resin is a chemical-resistant, high-temperature engineering thermoplastic which has many industrial applications, including injection molded parts and electronic components. During injection molding of certain poly(arylene sulfide) resins, corrosion of the metal parts of the mold can occur. Such corrosion of metal molds can be very costly, and attempts have been made to modify the poly(arylene sulfide) molding composition to reduce the tendency of such poly(arylene sulfide) compositions to corrode the metal surfaces of the molding equipment. One solution to the mold corrosion problem is given in U.S. Pat. No. 4,017,450, in which various chemical additives are disclosed as mold corrosion-inhibiting additives for poly(arylene sulfide) molding compositions.
It has been found, however, that such additives, while they are effective for reducing the corrosiveness of the poly(arylene sulfide) molding compositions, can sometimes bring about a reduction in the insulating ability and strength of the molded part in environments marked by high humidity and temperature. It would be desirable to produce a poly(arylene sulfide) molding composition which exhibited low mold corrosiveness, good insulating properties and retention of strength in moist environments.
In a different application, it has been found in electronic components that metal electrical leads are subject to corrosion when the electronic component includes a poly(arylene sulfide) part in contact with a liquid electrolyte. This is often seen in electrolytic capacitors having a liquid electrolyte in contact with molded poly(arylene sulfide) resin, and a similar problem is encountered in integrated circuits in moist environments. These problems are most notable when the leads are electrically biased. It would be desirable to reduce this corrosion in electronic components having poly(arylene sulfide) in contact with moisture or a liquid electrolyte.
It is therefore an object of the invention to provide a poly(arylene sulfide) molding composition which has a reduced tendency to corrode molds and acceptable electrical and mechanical properties in moist environments. It is a further object to provide electronic components comprising poly(arylene sulfide) parts in contact with a liquid electrolyte. It is a further object to provide a method of reducing corrosion of metal molding equipment.